Board Thread:Pokémon Help/@comment-32206650-20171028135714/@comment-27248965-20171031090237

The 1/512 is a fraction showing the rate, if you want to know the percentage, multiply it by 100. If you don’t have Ability Charm, you cannot get Wild Hidden Ability Pokémon in PBB, while the chance to breed Hidden Ability offspring is indeed 1/512. If you have bought Ability Charm, you gain a 1/512 chance for finding Hidden Ability Pokémon in the wild, and the rate for breeding Hidden Ability offspring is doubled to 1/256.